Spacing member used in forming bifocal lenses



M. A.,LAABS SPACING MEMBER USED IN FORMING BIFOCAL LENSES Filed May 51. 1921 INVENTOR MAX ALA/Q55 F/G]? BY ATTORNEYS same o d. is, was.

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MAX ALFRED LAABS, OF SOUTHBRIDGE,

' OPTICAL COMPANY, OF SOUTHBRIDGE TION MASSACHUSETTS.

MASSACHUSETTS, ASSIGIN'OR TO AMERICAN MASSACEUSEITS. A VOLUNTARY ASSOCIA- SPACING MEMBER. USED IN FORMIN BIFOCLAL LENSES.

a Application filed May 31, 1921. Serial No. 473,841.

' the manufacture of lenses and has particular reference to the production of bifocal or multifocal lenses.

One of the leading objects of the present invention is the provision of a novel and improved process for use in uniting the parts of what is commonly termed a fused bifocal lens, and has particular reference to the manner in which the parts are held during the fusing operation so that the air is allowed to gradually escape and at the same time so there will be no interposed wedges, spacing members, or the like in the final or completed blank.

A further object of the present invention is the provision of a novel and improved character of spacing member for use in fused bifocal lens production.

Other objects and advantages of my im proved construction should be readily apparent by reference to the following specification taken in connection with the accompanying drawings, and it will be understood that I may make any modifications in the specific details of construction shown and described within thescope of the appended claims without departing from or exceeding the spirit of my invention.

Figure I represents a plan view illustrating the construction of a lens in accordance with my invention. 1

Figure II represents a sectional view as on the line IIII of Figure I.

Figure III represents a view similar to Figure II showingthe completion of the fusing operation.

Figure IV represents a perspective view of my improved spacing member.

Figure V'represents an enlarged fragmentary view illustrating the use of a slightly difierent form of spacing member.

I am aware that prior to my invention bifocal lensesh'ave been produced comprising a main or major blank 1 havin r formed thereina countersink 2 adapted to 'oeive a segment 3, the parts Ming cemented together or united by heating and fusion. Prior to my invention, however, it has been cus tomary' to insert a wedge or spacing member .under one side of the segment 3 to hold said side raised as the fusing operation starts, it havingbeen necessary for the segment to melt down over and around the spacin 'r member before the operation is completed? This has ordinarily resulted in the embed ding of the spacing member in the finished lens, which must be subsequently eliminated either by grinding or cutting off a portion of the lens to get rid of the spacing member, while frequently difliculty has been experienced due to the fact that the portion of the segment immediately adjacent the portion of the wedge would not properly set down into the countersink, leaving an un-united space which renders that part of the blank useless, and is liable to create a certain strain tending to separate the remainder of the blank if kept in stock for any considerable period.

My invention, therefore, consists primarlly in the production of a new and novel form of spacing member and an improved process of manufacture embodying said spacing member. This member, as is most clearly shown in the perspective view Figure IV, is generally of l. shaped form, comprising the base 4 having rising therefrom the upright portion 5, and being further provided with the shoulder or projection 6, which I make about two-fifths of a millimeter in width, the same being thus very narrow and practically unnoticeable.

In use I place thesegment 3 over the countersink 2 of the major blank and hold it in position by suitably cementing to the face of the major blank a plurality of l. shaped lateral brace members 7 to prevent sliding around or slipping of the segment on the main blank. I then interpose at any. suitable position between the blank and segment the shoulder 6 of the member 4-5, the member 5 bearing tightly against the edge of the segment which is held by the member 7 against sliding out of engagement therewith, while the member 6 extends under the segment but only a relatively inappreciable' amount. With the segment mounted this small amount is sutficient so that the blank will be initially held by the member 6, the

engagement being suficient to hold the edge of the segment raised until the entire segment is softened and in proper shape for fusion. The edge will besufiiciently soft so that it will slide down over the member 6 for proper uniting with the main blank. In this action there will be but slight distortion of the actual edge of the segment which is substantially unnoticeable, and being the raised portion of the lens will be ground away when the surface of the segment is brought down even with that of the major blank 1 during the grinding operation while there is no embedment whatever of the parts in the glass, and no vdiificulty in the removal of the'member 4-5.

It will thus be seen that briefly stated my process consists in laterally supporting the segment against sliding; movement, and additionally laterally engaging the same to hold it slightly spaced from the major blank atone edge only and in such manner that the heat required for fusion will soften the segment so it will move out of engagement gradually with the spacing member, freeing the spacing member so that it can be re-utiliied and the parts united without interfering with the utility of the segment as an entirety and without leaving any perceptible mark on the blank.

Figure V illustrates the spacing member as of slightly difi'erent form, being substantially in the shape of a pyramid or a wedge 8 having the slight shoulder as at 9 on which one edge of the lens rests, the pyramid invoess being firmly seated on the surface of the major blank in the one case and in the other the projection being so slight as to allow the lens to readily move downward past the same without appreciable distortion or without causing the wedge or spacing member to be molded into the blank.

I claim: I 1. A spacing member for fused bifocal lenses, comprising a major portion and a segment portion, comprising a body memher having an inward projection adapted to underlie the edge of the segment portion and a raised element adapted to abut the edge of the segment portion.

2. A spacin member for use in the formation of fused ifocal lenses having a major portion and a segment portion comprising MAX ALFREDLAABS.

Witnesses:

SUsAN GASAZZA, Anon G. HASKELL.

whereof I have ailixed my 

